14
Table 10. Control Functions: Low Speed Signals Timing Characteristics
The following characteristics are dened over the Recommended Operating Conditions unless otherwise noted.
Parameter Symbol Minimum Maximum Unit Notes
TX_DISABLE Assert Time t_o 10 µs Note 1 , Fig. 6
TX_DISABLE Negate Time t_on 2 ms Note 2 , Fig. 6
Time to initialize, including reset of TX_FAULT t_init 300 ms Note 3 , Fig. 6
TX_FAULT Assert Time t_fault 1 ms Note 4 , Fig. 6
TX_DISABLE to Reset t_reset 10 µs Note 5 , Fig. 6
RX_LOS Assert Time t_los_on 100 µs Note 6 , Fig. 6
RX_LOS Deassert Time t_los_o 100 µs Note 7 , Fig. 6
Notes:
1. Time from rising edge of TX_DISABLE to when the optical output falls below 10% of nominal. A 10 ms interval between assertions of TX_
DISABLE is required.
2. Time from falling edge of TX_DISABLE to when the modulated optical output rises above 90% of nominal.
3. Time from power on or falling edge of TX_DISABLE to when the modulated optical output rises above 90% of nominal and the Two-Wire
interface is available.
4. From power on or negation of TX_FAULT using TX_DISABLE.
5. Time TX_DISABLE must be held high to reset the laser fault shutdown circuitry.
6. Time from loss of optical signal to Rx_LOS Assertion.
7. Time from valid optical signal to Rx_LOS De-Assertion.
Parameter Symbol Minimum Maximum Unit Notes
TX_DISABLE Assert Time t_o_twi 100 ms Note 1
TX_DISABLE Negate Time t_on_twi 100 ms Note 2
TX_FAULT Assert Time t_fault_twi 100 ms Note 3
Rx_LOS Assert Time t_loss_on_twi 100 ms Note 4
Rx_LOS Deassert Time t_loss_o_twi 100 ms Note 5
Analog parameter data ready t_data 1000 ms Note 6
Two-Wire Interface Ready t_serial 300 ms Note 7
Write Cycle Time Parameter t_write 80 ms Note 8
Two-Wire Interface Clock Rate f_serial_clock 400 kHz Note 9
Time bus free before new t_BUF 20 ms Note 10
transmission can start
Table 11. Control Functions: Two-Wire Interface Timing Characteristics
The following characteristics are dened over the Recommended Operating Conditions unless otherwise noted.
Notes:
1. Time from two-wire interface assertion of TX_DISABLE (A2h, byte 110, bit 6) to when the optical output falls below 10% of nominal. Measured
from falling clock edge after stop bit of write transaction.
2. Time from two-wire interface de-assertion of TX_DISABLE (A2h, byte 110, bit 6) to when the modulated optical output rises above 90% of
nominal.
3. Time from fault to two-wire interface TX_FAULT (A2h, byte 110, bit 2) asserted.
4. Time for two-wire interface assertion of Rx_LOS (A2h, byte 110, bit 1) from loss of optical signal.
5. Time for two-wire interface de-assertion of Rx_LOS (A2h, byte 110, bit 1) from presence of valid optical signal.
6. From power on to data ready bit asserted (A2h, byte 110, bit 0). Data ready indicates analog monitoring circuitry is functional.
7. Time from power on until module is ready for data transmission over the two-wire interface (reads or writes over A0h and A2h).
8. Time from stop bit to completion of a 1-8 byte write command. For a one to four byte write the maximum cycle time is 40ms and for a ve to
eight byte write the maximum cycle time is 80ms.
9. Module may clock stretch for f_serial_clock greater than 100 kHz.
10. Between STOP and START. See SFF 8431 Section 4.3
